Respirators are commonly worn over the breathing passages of a person for at least one of two common purposes: (1) to prevent impurities or contaminants from entering the wearer's breathing track; and (2) to protect other persons or things from being exposed to pathogens and other contaminants exhaled by the wearer. In the first situation, the respirator is worn in an environment where the air contains particles that are harmful to the wearer, for example, in an auto body shop. In the second situation, the respirator is worn in an environment where there is risk of contamination to other persons or things, for example, in an operating room or a clean room.
A variety of respirators have been designed to meet either (or both) of these purposes. Some respirators have been categorized as being “filtering face-pieces” because the mask body itself functions as the filtering mechanism. Unlike respirators that use rubber or elastomeric mask bodies in conjunction with attachable filter cartridges (see, e.g., U.S. patent RE39,493 to Yuschak et al.) or insert-molded filter elements (see, e.g., U.S. Pat. No. 4,790,306 to Braun), filtering face-piece respirators are designed to have the filter media cover much of the whole mask body so that there is no need for installing or replacing a filter cartridge. Filtering face-piece respirators commonly come in one of two configurations: molded respirators and flat-fold respirators.
Molded filtering face-piece respirators have regularly comprised non-woven webs of thermally-bonded fibers or open-work plastic meshes to furnish the mask body with its cup-shaped configuration. Molded respirators tend to maintain the same shape during both use and storage. Examples of patents that disclose molded filtering face-piece respirators include U.S. Pat. No. 7,131,442 to Kronzer et al, U.S. Pat. Nos. 6,923,182, 6,041,782 to Angadjivand et al., U.S. Pat. No. 4,850,347 to Skov, U.S. Pat. No. 4,807,619 to Dyrud et al., U.S. Pat. No. 4,536,440 to Berg, and Des. 285,374 to Huber et al.
Flat-fold respirators—as their name implies—can be folded flat for shipping and storage. They also can be opened into a cup-shaped configuration for use.
Molded respirators have two general orientations when folded flat for storage. In one configuration—sometimes referred to as a “horizontal” flat-fold mask—the mask body is folded crosswise such that it has an upper portion and a lower portion. A second type of mask is referred to as a “vertical” flat-fold mask because the primary fold is oriented vertically when the mask viewed from the front in an upright position. Vertically-folded masks have left and right portions on opposing sides of the vertical fold.
Nose clips are commonly used on both horizontal and vertical flat-fold filtering face-piece respirators to achieve a snug fit over the wearer's nose. Conventional nose clips commonly take the form of malleable, dead soft, linear, strips of aluminum—see, for example, U.S. Pat. Nos. 5,558,089, 5,307,796, 4,600,002, 3,603,315; see also U.K. Patent Application GB 2,103,491 A. During use, nose clips typically are bent the most at the center—that is, over the bridge of the wearer's nose. Unlike horizontal masks, a vertical mask has the nose clip pre-folded into a symmetrical v-shape during storage. Therefore, when a vertical mask is opened before use, the nose clip is opened at the same time and helps place the mask into a symmetrical cup-shaped configuration for donning. This configuration makes the vertical mask easy to don and to adjust for proper fitting. In contrast, because a horizontal mask lies in a generally flat configuration on the mask body when in the storage condition, the vertical or longitudinal axis of symmetry is not readily identifiable. Unlike vertical masks, horizontal masks do not arrive from the factory folded about the longitudinal axis. Horizontal masks therefore lack an indication of symmetry, which allows the user to rapidly identify the centerline of the nose clip for bending purposes. Examples of horizontal flat-fold respirators are shown in U.S. Pat. Nos. 6,568,392 and 6,484,722 to Bostock et al. An example of a vertical flat-fold mask is shown in U.S. Pat. No. 6,394,090 to Chen.
Filtering face-piece respirators must be able to maintain a snug fit to the wearer's face to achieve either of the above-stated purposes for protecting the wearer and other persons or things from contamination. Known respirators can, for the most part, match the contour of a person's face over the cheeks and chin. In the nose region, however, there is a more drastic change in contour, which makes it more difficult to achieve a snug fit over that portion of the wearer's face. Failure to obtain a snug fit allows air to enter or exit the interior of the respirator without passing through the filter media. When inhaled and exhaled air is not filtered, contaminants may enter the wearer's respiratory system or others may be exposed to contaminants exhaled by the wearer. In addition, the wearer's eyeglasses can become fogged by exhaled air that escapes from the respirator interior over the nose region, making visibility more troublesome.
To properly conform a nose clip over the bridge of a wearer's nose, the wearer should be able to properly locate the centerline or line of symmetry of the nose clip. Desirably, the wearer would like to bend the nose clip at the center such that there are equal portions on each side of the wearer's nose when the mask is worn. Unless the respirator is a vertically folded mask, the respirator wearer may have difficulty locating the nose clip centerline before bending the nose clip. Some wearers may not properly identify the centerline of the nose clip and therefore may make an unsymmetrical bend prior to donning the mask. Although this non-symmetrical bend may later be corrected by the wearer after the mask body has been donned, the wearer must know to make this change. It would be beneficial to not have to make this correction in the first place.